Predicting Contract Duration for Building Construction: Is Bromilow’s Time-Cost Model a Panacea?

Abstract

To predict project duration with reasonable accuracy is a problem of continual concern and interest to researchers and industry practitioners. Consequently, several research studies have focused on this subject, and thus multiple models have been developed. Notwithstanding the conflicting findings of its predictive veracity, the 45-year-old “time-cost” model of Bromilow remains the baseline, to which the outcomes of most developed models are compared. However, the applicability of the original time-cost model to the construction industry in the State of Kuwait is yet to be determined. The objectives of this case study, therefore, are to examine the validity, and hence the applicability, of the time-cost model to estimate contract durations for building construction in the State, and to propose an alternative model, taking into consideration other potentially influential project scope variables on time performance. To this end, relevant data for 113 residential and 74 office buildings, which were completed during the period 2004–2010, were collected by a questionnaire survey and subsequently analyzed using both the time-cost model and a multiple linear regression model comprising the project construction area as well as the number of floors above and below ground. While the results obtained further affirm the predictive ability of Bromilow’s time-cost model, a comparison between the outcomes of both models tested demonstrates that, on average, the multifactor model proposed is associated with an enhanced prediction accuracy of 16 and 14% for residential and office buildings, respectively, and therefore can be deemed more suitable for forecasting local construction duration for the building types investigated.